Referring to R.O.C. patent publication No. 414339, a conventional power supply includes at least a power supply module and a control circuit. The power supply module is coupled in a parallel fashion. Each power supply module has at least one commutation circuit, a main power source, a non-stop power source and a PWRGD (power good) generation circuit. The commutation circuit has an input end to receive city power (AC) and rectify the AC power to a DC voltage, and connect to one end of the main power source and the non-stop power source. The main power source is electrically connected to the PWRGD generation circuit and has a voltage (+5V) output end. The non-stop power source is electrically connected to a switch control unit of the main power source and has a non-stop voltage (+5V) output end. The main power source switch control unit has one end electrically connected to a main board and another end connected to the main power source and the PWRGD generation circuit. When an AC power source inputs to the commutation circuit and has been rectified, the non-stop power source and the main power source connecting to the commutation circuit generate respectively a non-stop voltage and a main voltage; meanwhile the non-stop power source generates a +5V non-stop voltage to the main board. The main board connecting to the main power source switch control unit determines whether to activate the main power source of the power supply module. If it is positive, the main board transmits a Low (below 0.4V) potential ps-on (power-supply-on) signal to a control signal receiving end of the main power source switch control unit, and the main power source switch control unit transmits a control signal to activate the main power source. When the main board transmits a High potential ps-on signal, the power supply stops operation and the system stops operation.
The power supply conforming to standard EPS (encapsulation security payload) specifications now on the market has a power transmission port of 24 pins. The 16th pin is a ps-on signal pin. The power supply conforming to ATX (advance technology extended) specifications has a power transmission port of 20 pins, and the 14th is the ps-on signal pin. The power transmission port is coupled with a connection line which has a coupling port linking to a computer main board and a connection port on another end connecting to the power transmission port of the power supply to transmit electric power at a plurality of potentials (such as +5Vdc, +3.3Vdc, +12Vdc and the like). The ps-on High/Low signals of the main board are transmitted to the power supply through the 16th pins of the coupling port and the power transmission port to control ON and OFF of the power supply. Take the power transmission port conforming to the standard EPS specification as an example, the voltage specification and signal pin functions are defined, from the first pin to the 24th pin in this order; as +3.3Vdc, +3.3Vdc, GND, +5Vdc, GND, +5Vdc, GND, POK, +5Vsb, +12Vdc, +12Vdc, +3.3Vdc, +3.3Vdc, -12Vdc, GND, PS-ON, GND, GND, GND, N/C, +5Vdc, +5Vdc, +5Vdc, GND. The coupling port, from the first pin to 24th pin, also is defined the same way. The power supply output cords now on the market all have a error free structure to prevent the connection port or coupling port from being inserted at a mistaken angle and resulting in damage of the main board or power supply. However, the conventional error free structure cannot prevent the coupling port that should be connected to the main board from being mistakenly connected to the power supply, or the connection port that should be connected to the power supply from being mistakenly connected to the main board. If the connection port and the coupling port are connected in the wrong way to the main board and power supply, when the machines are started, as the pins on the connection port and coupling port responsible for transmission of the ps-on signal are located on the same 16th pin (or 14th pin for the 20-pin connection port conforming to ATX specifications), the ps-on signal issued by the main board will be transmitted though the connection port and the 16th pin (or 14th pin) of the coupling port to the power supply, and the main power source will be set ON and cause damage of the main board. It will create serious consequence. Moreover, the power transmission port of the conventional power supply and the electric connection zone of the internal circuit board have a mating pin configuration to match the pin position of the coupling port of the main board. This makes circuit configuration of the circuit board of the power supply inflexible. Wiring of the pins on the power transmission port to the electric connection zone of equal potential on the circuit board is tortuous and more difficult. This results in a higher production cost.